The present invention relates to a two-dimensional code generation method, a two-dimensional code, a two-dimensional code recognition method, and an image recognition device.
A two-dimensional code has been known in which modules representing data are placed two-dimensionally based on predetermined format information. The two-dimensional code allows a large amount of data to be read using a narrow region in comparison with a one-dimensional code. Japanese Patent No. 2938338 discloses a related-art technology, for example.
When using such a two-dimensional code for card identification or the like, the two-dimensional code is printed on the front surface or the back surface of the card using a visible ink or an invisible ink which absorbs infrared rays and the like.
As shown in FIG. 46, a rare card can be relatively easily forged by a patch.
For example, it is possible to take measures against forgery by introducing an advanced technology in the card. However, this increases the manufacturing cost, whereby the profitability is reduced.
It is also possible to take measures against forgery by printing a minute pattern on the card. However, this method requires a high-performance camera for reading the card, thereby making it difficult to read a number of cards at one time using an inexpensive camera.